Stay bolt



Sept 421923. 1,466,686

w. zwlLLlN e STAY BOLT File d Nov. 28, 1919 INVENTOR BY M ATTORNEYS 1B contact with the threads in. the seat.

Patented Sept. 4, i923.

PATENT orties.

WILI-IELH ZVTILLINQOF 'osrmnaucx, GERMANY.

IsTAY norm.

Application filed November as, 1919.. semi no. 341,311.

To all whom it may 0mm.-

lle it known that I, /VILHELBL ZWIL ING, a citizen of the German Empire,residing at (lsnabruck, Germany, have invented certain new and useful Improvements in Stay Bolts (for which I have filed an application in Germany on September 17,1918, Patent No.

pressure at the joint without leaking. The

present application is directed to the structure of the bolt; while in'iy copending application, Serial No. att2,877,'filedFebruary 5, 1921, is directed to the method. of securing the bolt.

When a threaded bolt, such as a stay bolt or the like, is fixed by screwing it into a threaded hole or seat in a boiler wall or the like, great difliculty is experienced in rendering the joint sufficiently tight to with- Stand hlgh pressure without leaking. This is especially the case where the usual cop per bolts are replaced by iron bolts. I

In order to overcome the above di'l'liculty I it has been proposed to employ "for the bolt a hollow tube having externalscrew threads at an end, into which tube is forced, after the tube has been screwed'into its seat, a tapered or conical-shaped die for the purpose of spreading out the end of the tube and forcing the threads on it into intimate This arrangement has the disadvantage that the spreading eli'ect takes place only adjacent the mouth of the tube and. the intimate contact of the threads is thus only secured along a relatively small axial distance. My improved staybolt is designed to obviate these difiiculties, and I have also provided a stay bolt having a removable die. I employ a bolt having a threaded end provided with a substantially cylindrical cavity; and, after the bolt has been screwed into its seat in the boiler wall or the like, I spread out or widen the cavity and thus the threaded end by forcing into the cavityasubstantially cylindricaldie of greater diameter than the cavity, or, better still, by successively inserting in the cavity a plurality of such dies,

the successive ,dies being of gradually increasing diameter. A sultable appliance such as a pneumatic hammer, hydraulic press, or the like, 15 preferably employed iorinsert'ing the dies. Further', means are p'i'ovided, associated with the die, forwithdrawing the latter, as will in, detail hereinafter.

In order to prevent the die tromtouching the bottoin of the cavityI preferproviding be described more it with a flange at a distance from its end less than the length of he cavity, such. flange resting on the edge of the said cavity when the die is forced in and thus preventing the die from progressing any further.

In order to facilitate the withdrawal or removal of the die from the cavityl prefer providing itwit-h screw threading or placing an externally screw-threaded ring on the die, said ring being held thereon by a. cotter or the like engaging the ring and passed through a slot in the die head. When a nut is screwed onto the die or cylinder and up against the edge of the bolt or the boiler wall it serves to withdraw the die.

Inthe drawings aiiixed to this specification and forming part thereof 1 have illustrated the preferred form of a stay-bolt and the means for fixing it in place accordlng to my invention,

Fig. 1 being a longitudinal section of the bolt and a portion of the wall in which it is fixed, while Fig. 2 is a similar view of the bolt showing the die employed in widening a cavity of the bolt and the means for withdrawin it.

eterring to the drawings, (z'and Z) are the walls to be braced and a is the stay-bolt. (Z, (Z are the screwthreaded' ends of the bolt, and e, e are longitudinally extending substantially cylindrical cavities provided therein, said cavities being connected in this case by the usual boring or tell-tale hole h. The ends (Z, (Z of the bolt are represented as of larger diameter than the bodytc; this is done in order that a sulliciently large cavity portion of the die is cylindrical; and, for this reason, when it is inserted into the cavity it expands the walls thereof outwardly to the same extent along the full length of the expanded portion. '12 is the annular flange formed on the die to prevent its point from touching the bottom of the cavity. m is the threaded ring fitting on the head of the die, and 7c is the cotter passed through the die head, and serving as an abutment for the ring when the nut Z fitting in its threads is being screwed down upon the wall e in order to extract the die. In the drawing the die is represented with a hemispherical point, but it may be formed differently according to requirements I claim 1. Stay-bolt securing means, comprising in combination, a staybolt having an end provided with external screwthreads and with a longitudinally extending cylindrical cavity; and a die. having a cylindrical active portion of greater diameter than the diameter of said cavity, adapted to be inserted into said cavity, the die being provided with a flange adapted to engage the edge of the wall of the cavity to limit its movement into the cavity.

2. Stay-bolt securing means, comprising in combination, stay-bolt having an end provided with external screw-threads and with a loiigitudinally extending cylindrical cavity; a die, having a cylindrical active portion of? greater diameter than the diameter of the cavity, adapted to be inserted into said cavity; and means for withdrawing said die. I

3. Stay-bolt securing means according to claim 2, in which the means for withdrawing the die comprise screw-threads associated with said die and a screw-threaded nut adapted to engage said screw-threads and when screwed thereon to abut against fixed Inemberother than said die to withdraw the die.

Stay-bolt securing means according to claim 53, in which the means for withdrawing the die comprise an externally screwthreaded sleeve secured to said die, and a screw-threaded nut adapted to be screwed on to said sleeve and to abut against a fixed member other than said die to withdraw the die. l

in testimony whereof I afiix my signature.

WILHELM ZWILLING. 

